Radical induced damage ofMicrococcus luteusbacteria monitored using FT‒IR spectroscopy

Oxidative damage induced by ascorbic acid (AA) and hydrogen peroxide (H2O2) was monitored by Fourier transform infrared spectroscopy (FT-IR); it appeared as a rapid and convenient means to follow the biochemical changes generated in the culture media of the yellow-pigmented Micrococcus luteus. Beyond a threshold of 20 mM for AA and of 40 mM for H2O2 (final concentration), antioxidant systems were overwhelmed and significant changes were observed in the bacterial spectra, particularly in the 1430-900 cm −1 region; this spectral window provided large information about carboxylate groups, phosphate-carrying compounds and polysaccharides implicated in the radical process. The spectroscopic results indicated that for the same final concentration, the toxicity of H2O2 was less important than that of AA toward M. luteus cells, although H2O2 had a more damaging effect on proteins. Thus, FT-IR spectroscopy was an appropriate physico-chemical tool suitable in biochemical and clinical research for early characterization of any type of radical aggression, and for rapid detection of the damage intensity.